In meat, produce and general food vending and storage establishments that usually store large amounts of such perishable products, it is an ever present hazard that the establishment's refrigeration system could fail, either in its totality or in parts, thereby causing substantial losses from spoilage.
Such hazard is present especially during the hours when no attendants are available to take remedial actions.
Inventors have in the past sought solutions to this problem.
U.S. Pat. No. 3,544,722 by C. Hartfield et al., issued Dec. 1, 1970 entitled Security System describes a general alarm system for summoning assistance in response to a plurality of mishaps, such as break-in, fire, cold storage failure and so forth in response to sensors. The system provides automatic dialing to preselected telephones and depends on the mere presence of a human voice that answers the call as confirmation of receipt of the call. Such reliance on the mere presence of a voice may be disceiving, since the wrong party might answer and not understand the message, or the answer could be produced by an answering machine.
U.S. Pat. No. 3,441,929 by W. E. Coffer et al issued Apr. 29, 1969 entitled Remote Reporting System describes a general alarm system for reporting burglary, fire, refrigeration failure, etc. It depends on signalling a dedicated receiving station and indicate the different conditions by means of signals generated by motor driven cams.
U.S. Pat. No. 4,028,688 by J. B. Goleman issued June 7, 1977, entitled Refrigeration Unit Air Temperature Detection Alarm System describes a refrigeration alarm system comprising temperature sensors, automatic telephone dialer and recorded message announcer. It also describes the use of a wireless radio connection between freezer compartments and the alarm system.
The system provides no means for verification of the receipt of the alarm message.
U.S. Pat. No. 4,146,886 by S. W. Timblin issued Mar. 27, 1979 entitled Freezer Alarm With Extended Life describes a freezer alarm device for locally indicating a freezer malfunction. It has no remote reporting capability.
U.S. Pat. No. 4,278,841 by Regennitter et al., issued July 14, 1981, entitled Multiple Station Temperature Alarm System describes a freezer monitor system with wireless radio connection between the freezer compartments and the alarm system. The invention also describes an automatic telephone dialer combined with a recorded message circuit to deliver a message when the call is answered.
Nowhere in the prior art known to the applicant is there a disclosure of an arrangement for securing that the alarm message that has been automatically dialed through a telephone connection has actually been received and understood by an answering party who is prepared to deal with the alarm situation.
The present invention describes an alarm system that requires an affirmative response code that is detected by the alarm sending system and confirms that the answering person anticipates the alarm call and is prepared to deal with it. The present invention has several other novel attributes that contribute to the construction of a system that is failsafe to a high degree.
The present invention further overcomes earlier problems by introducing a refrigeration monitor system that offers several safeguarding features by means of a highly flexible form of control best known as stored program control. Such a control, not only allows a high degree of flexibility in adapting a refrigeration monitor system to changing requirements as they are found from one establishment to the next, but it also allows the designer of such a system to add features that in older systems with hardwired controls would have been very difficult to realize.
The introduction of stored-program control of complex systems has become economically feasible in recent years with the introduction of the so-called micro-processor with associated memory blocks that may contain control programs with literally thousands of system commands and instructions.
There are several books describing the operation and concepts of stored program control. One such book is "Microcomputer-Based Design" by John B. Peatman, published by McGraw-Hill and having Library of Congress catalog number ISBN-0-07-049138-0.
The use of a refrigeration monitor system according to the present invention has the additional advantage that the physical construction of the system may be based on readily available hardware components, that are relatively simple in operation, are very reliable and are relatively inexpensive and have moderate power drain.
It is therefore a primary object of the present invention to provide a refrigeration monitor system that is failsafe to a high degree without undue complexity.
It is another important object of the invention to provide a refrigeration monitor system that is capable of rendering a high degree of utility by means of mutually cooperating features.
It is another important object of the invention to provide a refrigeration monitor system that is capable of rendering a high degree of utility without undue complexity as it relates to its physical construction.
It is still another object of the invention to provide a refrigeration monitor system that is capable of rendering a high degree of flexibility and utility without undue complexity or cost.
It is still another object of the invention to provide a refrigeration monitor system that is capable of rendering a high degree of flexibility and utility without the need for excessive power drain.
Other objects and advantages of the invention will become clear in the course of the following description.